This invention relates to provisions for aligning the reticules of a telescopic sight (scope). More particularly it relates to alignment devices or methods used to true the crosshairs (which represent the vertical and horizontal axes) of a scope with respect to the bore axis of a firearm during installation to eliminate any xe2x80x9ccantingxe2x80x9d of the mounted telescopic sight within its mount. In addition, it relates to a provision to indicate the setting of eye relief during installation.
Virtually all currently marketed mounting devices for attaching telescopic sights to firearms incorporate a set of clamping rings attached to the firearm by various means. During installation the installer must first attach the mounting system to the firearm, then carefully locate the scope within its mounting rings to meet two criteria:
1) Proper eye relief (distance of the ocular lens of the scope from the shooter""s eye in the firing position). This is achieved by sliding the scope fore or aft in its rings until the proper position is achieved. Proper position can be determined by measuring the distance from the shooter""s eye as he holds the firearm in the shooting position and setting it in accordance with the manufacture""s specification. Alternatively it can be done by having the shooter determine when the image completely fills the ocular lens as the firearm is held in the shooting position and affixing the scope in that location. This setting is important for proper optical function of the scope; and also to prevent injury to the shooter by contact of the scope to the shooter""s head as the firearm recoils upon firing.
2) Proper alignment of the vertical and horizontal axes of the scope (represented by the crosshairs of the reticule) with respect to those of the firearm""s bore line is achieved by rotating the scope in its rings until the axes of the scope are in alignment with those of the firearm. This is done by various methods. The most basic method, which is employed by most amateurs, is to rotate the scope while the shooter holds the rifle in the firing position until the crosshairs appear level against some reference structure or terrain feature. This method is inaccurate. If the axes are not correctly aligned the scope can still be sighted in at a given range, however, at any range other than the sight in range, sighting errors will be induced in both the horizontal as well as vertical.
Additionally during sight in, if an adjustment is made in either vertical (elevation) or horizontal (windage), an unwanted shift of aiming point will occur in the other axis as well. This can confound the sight-in process. Gunsmiths and more knowledgeable hobbyists employ more sophisticated methods requiring specialized equipment and procedures. One Patent (Palmer #442860) describes a fixture device used for this purpose.
After the scope is properly fixed in its mounts, the sight in process begins. The first step is to xe2x80x9cbore sightxe2x80x9d. Various methods and devices accomplish this process. It involves an approximate alignment of the sight line with respect to the bore line and occurs without actually firing the firearm. Finally, the scope is calibrated during actual firing at a target to achieve the desired point of impact with respect to the point of aim. This process, called xe2x80x9csighting inxe2x80x9d, makes final adjustments for variations in conditions and ballistics of the particular ammunition to be used.
The object of this invention deals with the phase of the installation process that occurs after the mounting rings have been installed on the firearm and before the sight in process begins.
This invention consists of visible markings placed on the scope tube body and the mounts for the purpose of providing a system or method of indexing a telescopic sight to its mounting hardware in order to align the reticule of the sight with the vertical axis of the firearm""s bore during installation. It also can be used to verify that the installed location has not shifted or been altered, and to provide a means to easily return the sight to its originally installed position should it be necessary to remove the sight from its mounting hardware. It is, therefore, the object of the present invention to provide an inexpensive, simple, intuitive, easy to use provision for quickly aligning the reticule of a firearm mounted telescopic sight with the vertical and horizontal axis of the firearm""s bore; and which overcomes problems of the prior art.
Another object of the invention is to likewise provide a reference for setting eye relief.
A still further object of the invention is to provide a feature that can be incorporated into existing designs of telescopic sights and mounting hardware either during manufacture or by retrofit.
A still further object of the invention is to provide a feature for quickly aligning reticules that requires no accessory devices, hardware, or fixtures.
A still further object of the invention is to provide a means of verification at a glance that the installed position has not changed.
A still further object of the invention is to provide for easily returning the telescopic sight to its originally installed position should it become necessary to temporarily remove it from its mounting hardware.
A still further object of the invention is provide a simple intuitive method which would enable an installer with little expertise to accurately install a telescopic sight in its mounts without the use of special tools, fixtures, appliances, or procedures.
A still further object of the invention is to provide the more experienced and exacting installer a visual reference for more precise refinements of the installed location than normally required, or for unusual settings.
The improvement provided by the features of this invention would provide for easier installation and in most cases better accuracy, thereby adding value to the products employing its features at minimal cost to the manufacturer.